package com.huawei;

import java.util.HashSet;
import java.util.Scanner;

public class HJ010 {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);

        String input = scanner.next();
        char[] array = input.toCharArray();
        HashSet<Character> set = new HashSet<>();
        for (char c : array) {
            int ASCLLCode = (int) c;
            if(ASCLLCode >=0 && ASCLLCode <= 127){
                set.add(c);
            }
        }
        System.out.println(set.size());
    }
}
